‘Is it halfway drinkable?’ Gundula Janowitz interrupts herself to check I’m happy with the tea she’s made, particularly worried that it might not be up to an Englishman’s exacting standards. Go back an hour earlier, and I’m hovering nervously outside in a quiet street in Vienna’s Wieden district, south of the famous Naschmarkt and west of Schloss Belvedere, plucking up the courage to press the ‘Janowitz’ buzzer.

I’m immediately put at ease by the mellifluous voice that welcomes me through the intercom and invites me to the second floor. There I’m greeted by the 79-year-old soprano – spritely and warm, a mixture of mischievous wit and effortless, old-world charm. She laughs as I offer to take my shoes off – ‘what on earth for?’ – and shows me through to an elegant drawing room.

We in fact start our conversation straight away. The tea can wait, she says, and does for a good three quarters of an hour. I’m there primarily to talk to the soprano about her memories of recording Wagner’s Ring with Herbert von Karajan, for Gramophone’s July cover feature, but the conversation ranges far and wide. Janowitz is herself a generous talker – at one point she even asks, to my slight embarrassment, ‘So how did you become interested in music?’

Her speaking voice, I like to imagine, is still distinctly identifiable as the voice heard on countless favourite recordings – as the Countess on Karl Böhm’s classic Figaro (the duettino from which chosen in Frank Darabont’s 1994 film The Shawshank Redemption to epitomise ethereal, otherwordly vocal beauty), for example, or soaring aloft in Karajan’s 1974 recording of Strauss’s Four Last Songs.

But she’s a singer – the possessor, indeed, of one of the most recognisable and beautiful voices ever captured on record – without the slightest diva-ish trait. And rarely can a former star of opera stage and concert platform have been so at ease with retirement: she clearly had no problems whatsoever in leaving behind a life of jet-setting from one major venue to another.

When we speak, though, she’s just returned for what is a rare visit to see an opera: a revival of the Karajan-directed Walküre at the Salzburg Easter Festival in which she sang Sieglinde half a century ago. It was the first time she’d actually seen the production. She enjoyed the closing scene, she tells me, but was less convinced by the interaction between the singers. ‘The most important thing for me as a singer was always to listen to your partner and answer them accordingly. When two people are having a conversation on stage, then it doesn’t matter how big that stage is – everyone will be watching.’

But this Salzburg trip was an exception: she never really goes to the opera, or to concerts either. Later on she tells me, when she returns with tea and a generous selection of Viennese cake – ‘please, have as many as you like!’ – that I’m the first person she’s ever invited to her apartment to talk about music. I will in all likelihood be the last too, she adds, quite matter-of-factly. She barely does interviews, she says.

Why not, I ask? ‘It doesn’t interest me. I sang, and I’ve stopped – done.’ But while these words might come across as brusque on the page or screen, they come across, in Janowitz’s gentle, beautifully modulated German, in a way that is simply honest. I scan them for even the slightest hint of regret, without success.

‘Then people ask why I don’t go to the opera. And I say: I wanted to sing. What others do doesn’t interest me. I enjoyed it when I had great colleagues or really beautiful voices next to me. But now I never listen to singing. I listen to chamber music, and I have a basket with all the Haydn symphonies next to my bed. I was away from home so much that I’m happiest now when I’m here at home in the evenings. I need my rest, and I read a lot’ – mainly history books, she tells me later, with a special focus on Berlin’s golden period of 1795-1806.

‘Two days a week I get my daughter’s dog – a little West Highland Terrier – to look after and we go walking. Once I week I go to the hospital and visit the sick. And then the week’s quickly over anyway! It’s a very calm life. Every day is important for me, and I’m very pleased that I can do it like that.’

I look around her drawing room, and beyond an antique engraved portrait each of Schubert and Mozart, the only memento of her career is a small black and white photo of her, relaxed and smiling, with Karajan, his arm around her. ‘The only photo of it at all is that one with Karajan, otherwise you’d never see that a singer lives here.’

Is there a piano in the apartment? ‘No, what for?’ she replies, straightforwardly. There’s still music in her life, though: ‘I’ve always been interested in music, and every day I go to sleep to a Haydn symphony – I hear the music and then I’m out. What better conclusion to the day?’

I probe a little more about her career, wondering if there are any chinks in the even-tempered, contented surface. Is there anything she regrets? ‘No,’ she answers calmly. ‘I believe a little that everything’s preordained throughout one’s life. So I’m not sorry about what didn’t happen, and I’m pleased about what did happen. But saying, “Ja, if only I’d been able to do that” – no, that’s not me. I’m pleased that I managed to do what I set out to do. I wanted to sing, because I couldn’t imagine a life without singing, but today I can imagine it very well: I don’t sing at all now, never. It was enough.’

The way that Janowitz is able to separate herself from her former career – she tells me she only first referred to it as a ‘career’ once she’d retired – is striking. The key, perhaps, is to be found in a touching story she recounts about what she did after her final concert, a remarkable 1999 Athens recital released for the first time to commemorate her 80th birthday.

‘When that final Liederabend came, I drove to a forest, stopped the car and went for a walk – to bid farewell to my voice. And I thanked it because – apart from a couple of occasions, and that was my fault – it never let me down, it was always there. It was really as if I was saying goodbye to a person. I said: “I’m saying farewell to you, and thank you for having accompanied me for so long.”’

Did it make her sad? ‘No, I wasn’t sad at all,’ she answers. ‘After 40 years, one is a little relieved!’ She did, however, find herself once accidentally reuniting herself with her old friend. ‘I did carry on doing masterclasses, and there was one where a singer wanted to do the Donna Anna aria, so “Non mi dir”. She tried it, and I said, “you know, before I talk about it, let me just show you what I mean, I’ll sing it to you.” I started to sing, and in the middle of it, in the slow section, I said to myself: “Oh my God! What are you doing – you’ve already said goodbye!” Then I pulled myself together, and I think it was the best Donna Anna aria I ever sang. But never again.’

A story about another masterclass brings us on to Janowitz’s view on the importance of creating your own interpretations as a singer. ‘I come from a time when there were no CDs,’ she explains, ‘and I used always to say, “please don’t listen to CDs, sit down with the notes, look at what Schubert meant with this or that, don’t listen to someone else.”’

She recalls an occasion where a young Taiwanese singer performed one of the Mignon-lieder for her, and kept on making the same mistake at a particular moment. ‘At the fourth time I said: “What silly cow have you been listening to?” She stood there and said, “your recording”. So I said, “Well I’m a silly cow, too!”’

Of her own attitude to interpretation, she saw herself, she says, as a ‘relay station’ – she uses the English phrase. ‘Here is the composer with the word, and here is the listener. We’re in the middle; we’re taking these works to the listeners’. For her, success in recital meant total quiet after a performance. ‘Then you know – a-ha! – I’ve been able to communicate this wonderful music.’

Her attitude towards he career more generally, it becomes clear, was one of straightforward professionalism, of comprehensive preparation and easy collegiality. As such, it was a working life that consisted, it seems, almost entirely of positive experiences. One exception was her recording of Fidelio with Bernstein. Behind-the-scenes wrangling had left her recording the work with a conductor who in fact would rather have had someone else.

‘But no one told me! I would have stepped down. And at the same time I was supposed to do the role with Solti in America. So I had to write to Solti: “Please be so kind and release me, because I have to sing it in Vienna”. Then I come to Bernstein and he didn’t even look at me – and Fidelio is difficult for a singer – and I thought, ‘what has he got against me?’

He should have called Gwyneth Jones, who he always wanted, instead. I wouldn’t have minded. But then Karajan was angry too, because I’d done Fidelio with Bernstein! But today, looking back, I have to say it was all good. And, after all,’ she adds with characteristic modesty, ‘one’s just a small cog’.

Karajan is of course one of the conductors Janowitz is most closely associated with. He invited her to the Vienna State Opera after she sang for him in September 1959, and they produced a string of recordings together up until her final appearance with him, in the Brahms Deutsches Requiem, in 1979. She recalls, in particular, the famous Four Last Songs, recorded in just two takes each, without breaks.

For him it was about music as ‘a “river”: the little errors he didn’t care about.’ At that recording, as she recalls, he said, ‘“We’ll do it without piano; we’ll do it straight away with the orchestra”, and I said, “yes please – bitte, gerne!” He’d just look at me and I should shake my head if I didn’t like what he was doing.

‘And so we began with the first song, “Im Frühling”, and he took quite a fast tempo. He looked at me, and I shook my head. He broke off and said, “We’ll start again”. And then he did it even faster. He looked at me again and I made the same gesture. He stopped and said’ – and here Janowitz mimics a hint of Karajan-esque impatience – ‘“Schneller kann ich nicht!”’. She adopts a gentle, patient tone: ‘“Aber langsamer!”, I replied’

Janowitz once described her favourite roles as being ‘the three As’- Mozart’s Donna Anna, Strauss’s Arabella and Agathe in Der Freischütz. With conductors, however, it’s a matter of all the Ks: ‘Knappertsbusch, Karajan, Klemperer, Kleiber, Kubelík – so many with “K”! I liked them all. But I always made sure that I’d prepared well, and when something wasn’t right, I would go to the conductor myself: “Can you take this or that phrase more slowly?” It wasn’t a problem at all. I was no revolutionary.

‘And Kempe!’ We remember another ‘K’ together. ‘Ja, ja, natürlich: Ariadne, Verdi Requiem, Lohengrin, Schubert Masses, Meistersinger – so much,’ she laughs. ‘I was able [to work] wonderfully with him. There was a true musician’ – she draws the distinction in German between ‘Musikant’ and mere ‘Musiker’. ‘If I’m going to be completely honest, if I was going to listen to anything by me, then I’d say it would be the Bridal Chamber scene from this Lohengrin with Kubelík. I imagine that that is how it should be. He did it wonderfully.’

But she is not easy to draw into talking about the many great singers she knew or shared stages with, a result, one suspects, both of her discretion and of simply having left that life behind. She is generous about certain colleagues. Vickers, her Siegmund with Karajan, she calls ‘Herrlich’ – wonderful – while Callas, whom she never heard live, she says cannot be described in words. ‘This technique, this power of expression – enorm, enorm! Unique!

‘I sang Figaro a lot with Mirella Freni,’ she continues. ‘Who of course was an unbelievable singer. And Christa Ludwig naturally, too.’ She still sees Ludwig regularly – they both live in Vienna – and together they undertook an extensive conversation on the stage of the State Opera (viewable on YouTube). But even this was approached with as much conscientiousness as ever: ‘We met six times beforehand and talked through it, otherwise it would have been embarrassing.’

Her greatest friend from the opera world, though, is Brigitte Fassbaender, and when we speak, Janowitz is looking forward to appearing ‘in conversation’ with her at the Garmisch Strauss Festival (Fassbaender is the festival’s director), where she is also due to be honoured with the ‘Ehrenplakette Richard Strauss’. There’s also a more casual plan with Fassbaender later in the year: they’re booked to go on a cruise to the Norwegian Fjords together. Janowitz laughs when I suggest they should take a camera crew with them.

And as I listen to back to my tape, I hear Janowitz’s trilling, uninhibited laugh sprinkle itself across the whole conversation with disarming regularity. Her sense of humour – quick and playful – is never far from the surface, and at one point she delights in regaling me with a Beecham story.

We nevertheless touch on some broader subjects that feel a little melancholy. She laments what she sees as a shortage of directors who really understand music; she recalls, with what feels like a hint of nostalgia, a time when, for Karajan productions in Vienna, the queue for standing places would wind its way three times around the Staatsoper building. ‘Those were really the golden years,’ she says.

‘And it’s really bad in Italy, the home of opera. There are houses there that are dead. It’s quite interesting that opera, apart from films and cinema, is the newest of the art forms – 500 years old, and in human history that’s nothing. It could just happen that it stops. I’ve always thought that you should get [opera] as a child or teenager – it doesn’t work later. And 50 years ago people had more time for themselves, to collect records and listen to them in the evening.’

Perhaps she’s informed by her own introduction to opera, of seeing Die Meistersinger von Nürnberg in Graz aged 10 – where she and her parents had moved from Berlin after the war. She made the decision to become a singer herself just two years later, and says she could never have imagined doing anything else. ‘I’ll always remember how my parents never said, “you’re mad!” Instead, they told me I could do it, when the time was right.’ Today she is amazed by how much she achieved in that career. ‘My daughter has all the programmes – I’m sure I’ll never look at them – but I still know exactly what I did.’

Does she have any advice for young singers? ‘You can’t advise … I want to, I have to, and I can.’ She repeats, ‘Ich will, ich muss, ich kann; those are the three maxims. Of course it was lovely when I had good colleagues beside me, but I wanted to sing – ich wollte singen.’

Deutsche Grammophon recently released a new 14-disc box-set called 'The Gundula Janowitz Edition', which gives a wonderful overview of her career. First Hand Records has released Janowitz's final recital, 'In Memoriam Maria Callas', recorded in September 1999.